Early diagnosis and early treatment of tumors is critical to improving tumor cure rates. The existing diagnostic means commonly used in clinical practices include chest X-ray, B-scan, CT, nuclear magnetic resonance (NMR), etc. and are often accompanied by procedures such as punctures and blood draws that make the patient suffer more and even may cause cross-infections. Moreover, these means cost much, and more importantly, tumors that can be detected by these means are mostly advanced tumors, leading to great pain and economic burden on the patient. Therefore, it is imperative to develop a detection method allowing easy and quick operation, low cost, high sensitivity and good repeatability.
The abnormal nucleotide metabolism in cancer cells produces monophenolic metabolites, specifically, tyrosine, p-hydroxyphenyl alanine, tryptophan and 5-hydroxyindoleacetic acid, present at contents much higher than those in normal individuals. These substances can be discharged through the urine and analysis of the contents of the monophenolic metabolites enables the inference of presence of cancer in the body. This allows early tumor detection and saves lives without adding expenses or causing the patient's fear and pain. However, some trace components or substances resulting from metabolic abnormalities caused by other diseases in the urine are also associated with mercuric and mercurous ions in the detection reagents to result in precipitates with colors, which may significantly affect the accuracy of the test results. Therefore, although the existing reagents for detection of urine metabolites are highly sensitive, they are associated with the false positive issue which significantly reduces the detection accuracy, leads to misdiagnosis and limits their application.